Parallel experiments on human subjects and laboratory primates with closely similar visual systems are utilized to study neural mechanisms underlying visual image displacement detection. Electrophysiological measures of retinal ganglion cell responses of rhesus macaque form the basis for a mathematical description of a single cell response to both stationary and displaced spots of light. Psychophysical measures of human sensation at a similar visual field site gives a measure of visual system performance. Using information theory, the performance of parallel channels of the mathematical descriptor will be calculated and compared to the information resolved by the human observer. Particular emphasis is placed on the primate phasic system and peripheral visual fields where the discrimination of form is poor but good sensitivity to image displacement is evident. To date, our studies have led to several interesting findings. The rapid adaptation of neural response to a stationary flash of light provides the phasic system with unique receptive field properties; this effect suggests that rapid adaptation may have an effect on the spatial resolution of image displacements. The rapid adaptation in the phasic system may provide the first example of non-linear synaptic transformation within a neural space subserving a sensory surface. The project seeks to confirm and extend these electrophysiological findings, perform psychophysical experiments and develop mathematical descriptions and theory.